Collaborative Research: Charge Transport in Helicoidal Molecular Crystals

合作研究：螺旋分子晶体中的电荷传输

• 批准号: 2116183
• 负责人: Stephanie Lee
• 金额: $ 29.72万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2116183&HistoricalAwards=false
• 关键词: Collaborative; Research; Charge; Transport; Helicoidal

Non-technical abstract Crystals are straight by definition. They have sharp edges and flat faces. They are polyhedra. However, molecular crystals that twist as they grow are remarkably common, albeit little known. More than one third of simple molecular crystals are capable of forming twisted morphologies. As a largely unexplored phenomenon, crystal twisting introduces a new dimension to materials design. Plastic electronic devices, e.g. foldable LCD screens, smart phones, computers, and solar panels, depend on the shapes of tiny crystals that carry electricity. This collaborative project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, uncovers at a fundamental science level the effect of twisted morphologies on the propagation of electrical current and light through crystals comprising organic semiconductors in order to usher in the next age of personal consumer electronic devices as well as critical technologies associated with renewable energy. Early results show that twisting boosts conductivity. Outreach activities embracing literature, art, history, and education reflect the themes of crystals and chirality (items that can be distinguished from their mirror image are chiral, for example a hand) that undergird these scientific efforts, with a focus on using intriguing aspects of twisted crystals as a platform to engage K-12 students in STEM-related activities in the NY metro area. Technical AbstractHelicoidal crystals with pitches from 1-500 microns can carry charge when grown from molecules that form traditional organic semiconductors. At the level of devices, twisting on these length scales can have critical consequences on light propagation and charge injection, extraction and hopping. To elucidate the general effect of twisting on such processes, a series of semiconducting compounds are induced to twist as they crystallize from the melt into thin films as part of this collaborative research, which is supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF. Conductive and photoconductive atomic force microscopy and charge mobility measurements using a field-effect transistor platform are performed on these helicoidal crystals as a function of pitch to determine the modulation of electric field- and photo-induced charge transport locally along and perpendicular to the twisting axes. As optoelectronic devices typically require specific crystal orientations within active layers for optimal performance, electrocrystallization is applied to molten organic conductors to collimate twisted crystals on electrode surfaces. Electrical magnetochiral anisotropy measurements, in conjunction with complete imaging polarimetry unique to the PIs' laboratories, are actualized in the search for chiral defects introduced via twisting. In doing so, this research uncovers fundamental mechanisms of crystal growth while addressing inherent limitations in the field of organic electronics, including large charge transport anisotropies along less accessible crystallographic directions and difficulties in tuning molecular interactions independent of molecular structure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术抽象 根据定义，晶体是直的。它们具有锋利的边缘和平坦的表面。它们是多面体。然而，尽管鲜为人知，但在生长过程中扭曲的分子晶体却非常常见。超过三分之一的简单分子晶体能够形成扭曲的形态。作为一种很大程度上未被探索的现象，晶体扭曲为材料设计引入了新的维度。塑料电子设备，例如可折叠液晶屏、智能手机、电脑和太阳能电池板都依赖于携带电力的微小晶体的形状。该合作项目得到了美国国家科学基金会材料研究部固态和材料化学项目的支持，在基础科学层面揭示了扭曲形态对电流和光通过有机半导体晶体传播的影响，以引领在个人消费电子设备以及与可再生能源相关的关键技术的下一个时代。早期结果表明，扭转可以提高导电性。涵盖文学、艺术、历史和教育的外展活动反映了晶体和手性（可以从其镜像中区分出来的物品是手性的，例如手）的主题，这些主题巩固了这些科学努力，重点是利用晶体和手性的有趣方面扭曲晶体作为一个平台，吸引 K-12 学生在纽约都会区参与 STEM 相关活动。技术摘要螺距为 1-500 微米的螺旋晶体在由形成传统有机半导体的分子生长时可以携带电荷。在器件层面，这些长度尺度上的扭曲会对光传播和电荷注入、提取和跳跃产生严重影响。为了阐明扭曲对此类过程的一般影响，作为这项合作研究的一部分，一系列半导体化合物在从熔体结晶成薄膜时被诱导扭曲，该研究得到了该部门固态和材料化学项目的支持美国国家科学基金会材料研究部。使用场效应晶体管平台对这些螺旋晶体进行导电和光电导原子力显微镜和电荷迁移率测量，作为螺距的函数，以确定沿和垂直于扭转轴的局部电场和光致电荷传输的调制。由于光电器件通常需要有源层内具有特定的晶体取向以获得最佳性能，因此将电结晶应用于熔融有机导体以准直电极表面上的扭曲晶体。电磁手性各向异性测量与 PI 实验室独有的完整成像偏振测量相结合，在寻找通过扭曲引入的手性缺陷时得以实现。在此过程中，这项研究揭示了晶体生长的基本机制，同时解决了有机电子领域的固有局限性，包括沿不易接近的晶体方向的大电荷传输各向异性以及独立于分子结构调整分子相互作用的困难。该奖项反映了 NSF 的法定使命通过使用基金会的智力价值和更广泛的影响审查标准进行评估，并被认为值得支持。

项目成果

Charge Transport in Twisted Organic Semiconductor Crystals of Modulated Pitch

• DOI: 10.1002/adma.202203842
• 发表时间: 2022-08-19
• 期刊: ADVANCED MATERIALS
• 影响因子: 29.4
• 作者: Yang, Yongfan;de Moraes, Lygia Silva;Shtukenberg, Alexander G.
• 通讯作者: Shtukenberg, Alexander G.

Transport in Twisted Crystalline Charge Transfer Complexes

• DOI: 10.1021/acs.chemmater.1c04003
• 发表时间: 2022-02-22
• 期刊: CHEMISTRY OF MATERIALS
• 影响因子: 8.6
• 作者: Yang, Yongfan;Zhang, Yuze;Kahr, Bart
• 通讯作者: Kahr, Bart

Chiral Crystals, Jack, Conductivity and Magnetism

• DOI: 10.1002/hlca.202200202
• 发表时间: 2023-05
• 期刊: Helvetica Chimica Acta
• 影响因子: 1.8
• 作者: B. Kahr;Yongfan Yang;S. Whittaker;A. Shtukenberg;Stephanie S. Lee

Collimating the growth of twisted crystals of achiral compounds

• DOI: 10.1002/chir.23558
• 发表时间: 2023-03-18
• 期刊: CHIRALITY
• 影响因子: 2
• 作者: Lozano, Idalys;Whittaker, St. John;Lee, Stephanie S.
• 通讯作者: Lee, Stephanie S.

Twisted tetrathiafulvalene crystals

• DOI: 10.1039/d2me00010e
• 发表时间: 2022-02-16
• 期刊: MOLECULAR SYSTEMS DESIGN & ENGINEERING
• 影响因子: 3.6
• 作者: Yang, Yongfan;Zong, Kai;Lee, Stephanie S.
• 通讯作者: Lee, Stephanie S.